Airbag, method of folding the latter, and device for carrying out the method

ABSTRACT

An airbag for an airbag module wherein, in the folded state, the airbag has at least one constriction and folds extending in an ordered and/or chaotic manner. Preferably, the constriction extends from the top of the airbag to the bottom and perpendicular to the plane of the expanded unfolded airbag.

FIELD OF THE INVENTION

The invention relates to an airbag, a method for folding same and adevice for carrying out the method.

BACKGROUND OF THE INVENTION

In order to be able to store an airbag in an airbag module it is knownto fold the airbag into a correspondingly small packet. Different typesof folding are known. Thus from U.S. Pat. No. 4,173,356, different typesof straight line folding are known wherein the folds run in rays from acentre towards the outside or approximately parallel to each other. Thedrawback with these folds is that they have to be collapsed at leastwhen used in a driver airbag module so that during unfolding of anairbag of this kind the internal pressure produced in partial areas ofthe airbag impede the opening of some folds. Furthermore the expense forfolding is considerable.

From DE 44 22 276 A1 an airbag is known for an airbag module wherein theairbag has main folds which run at least in part along closed tracksround an imaginary centre on the substantially empty spread-out airbag.The closed main folds describe preferably circular paths or ellipses ofslight eccentricity.

This path for the main folds has the advantage that the folded airbagcan open very rapidly and easily. More particularly during the unfoldingof such an airbag there is not the danger that the internal pressureproduced in partial areas of the airbag will prevent the opening offurther folds. This airbag can thereby be used for driver, passenger andside airbags. The drawback with this folding is that the expense formechanical folding is high.

SUMMARY OF THE INVENTION

The object of the present invention is to fold the airbag so that on theone hand it can be easily and completely unfolded and on the other theexpense of folding the airbag is reduced.

According to the invention, the airbag has in the folded position atleast one continuous constriction as well as ordered and/or chaoticfolds. More particularly, it is proposed that the folds in the areas ofthe airbag divided by the constriction run separated without overlappingthe constriction. In the case of an airbag with a top and bottom side,the constriction extends from the top side to the bottom side of theairbag. More particularly, the constriction extends in one embodiment atright angles to the plane of the spread-out unfolded airbag throughsame.

The advantage of this constriction is that it has a positive effectparticularly on the chaotic folding. The drawback with chaotic folding,that areas of the airbag overlap whereby unfolding of the airbag isimpeded, is substantially avoided by the provision of at least oneconstriction. Furthermore, there is the advantage that for differentshapes of airbag module, through one or more constrictions, it ispossible to spread out the folds to match the different shapes. Thespace available for the folded airbag can be utilized in optimum manner.

Depending on the selected form of the spread-out airbag, it can beexpedient to provide one, two or more constrictions in the airbag. Theairbag for a driver airbag module preferably has four constrictions.

In a further embodiment, at least one constriction is provided whichruns between the upper side and the lower side of the airbag. With thisembodiment owing to this constriction, the upper and lower parts of theairbag are separated at least in part, and both parts also have separatefolds. With this embodiment, the fact that the folds of the upper partdo not project into the folds of the lower part has a particularlyadvantageous effect on the all-round rapid unfolding of the airbag.Furthermore, with the constriction, the outer areas of the airbag aremoved inwards close to the gas generator or diffuser. Thus, duringunfolding of the airbag, apart from the accelerated expansion in themain unfolding direction, an expansion at right angles thereto is alsoachieved. By selecting the arrangement, number and depth of theconstrictions it is possible to accurately control the unfolding incertain directions.

One method for folding an airbag is characterized according to theinvention in that the spread-out airbag is constricted at least oncecontinuously on at least one side and that it is then folded and/orcompressed to the extent required for stowage in the airbag module.

It is expedient if the airbag is folded separately in areas which areseparated by a constriction.

In a first embodiment in the case of an airbag which has an upper sideand a lower side, the airbag is constricted from the upper to the lowerside.

The constriction carried out in the first stage represents a pre-foldingfor the following orderly or chaotic folding. These method steps allow asimple mechanical conversion since the production of a constriction andthe compression of the thus pre-folded airbag are simple procedures.

The airbag is preferably constricted at right angles to the plane of thespread-out airbag. However constrictions deviating from theperpendicular are also possible to obtain the advantages.

The airbag is constricted on one side or on several sides. The airbagfor a passenger airbag module is preferably constricted from one side.The spread-out airbag, which is only provided with the one constriction,has prior to compression the shape of a human molar tooth with tworoots. The airbag for a driver airbag module is preferably constrictedon four sides whereby the preferably take place simultaneously. Thespread-out airbag which is only provided with the four constrictions hasprior to compression the shape of a four-leaved clover.

During folding and compression of the airbag, the constrictionspreviously provided have the effect that the ordered and/or chaoticfolds produced are each only formed inside the area defined by theconstrictions, i.e. the folds do not overlap the constrictions.Overlapping of in particular the chaotic folds is thereby substantiallyavoided. The constrictions are also obtained after the chaotic folding.

In a further embodiment it is proposed that the airbag is constrictedbetween its upper and lower side and that then both sides are foldedand/or compressed separately.

A device for folding an airbag is characterized according to theinvention in that one tool each is provided for producing eachconstriction, that the spread-out airbag and the tool can be movedrelative to each other in the plane of the spread-out airbag and thatfolding tools and/or slider-like tools for compressing the airbag to thestorage size are provided above and/or at the side of the spread-outairbag.

In one embodiment it is proposed that the tool for producing aconstriction extends perpendicular to the plane of the spread-outairbag. The tool preferably extends at least over the height of theairbag in its folded position.

In a further embodiment it is proposed that the tool for producing aconstriction extends parallel to the plane of the spread-out airbag. Inthis embodiment the width of the tool is preferably less than thelargest width measurement of the spread-out airbag.

A sword-like tool can advantageously be provided for producing theconstriction. This tool has at least a height corresponding to theproposed height of the folded airbag so that the airbag is constrictedover the entire height when sliding the tool sideways into the airbag.

In a further embodiment a wire-like tool is provided for producing theconstriction and extends substantially at right angles to the spread-outairbag.

In preferred embodiments it is proposed that one sword-like or wire-liketool each is provided for producing each one constriction.

It is expedient for the prefolding of an airbag for a passenger airbagmodule to provide a tool so that a constriction is produced during itsoperation. For prefolding an airbag for a driver airbag module it isexpedient to provide four tools so that when operated four constrictionsare produced.

These sword or wire like tools as well as the slider-like tools forcompressing the airbag are to be operated mechanically and simply in anyknown way whereby a high processing reliability is achieved.

A further design of the tool is characterized in that a space isprovided for folding the airbag between a lower cover plate and an uppercover plate of which one is movable, that the sword-like tool runsbetween the cover plates and at right angles to same, that the space forfolding the airbag is restricted at the side by sliders which aredisplaceable between the cover plates, that in the lower cover plate anopening is provided for an airbag housing and next to this at least oneslider is provided which can be moved at right angles relative to thecover plates, and that in the upper cover plate in the area of theairbag housing an opening is provided in which a removable packing ramis mounted which can be moved at right angles to the cover plates andcontains a place holder which can be moved perpendicular to the coverplates.

The place holder has, at right angles to the direction of movement,roughly the cross-sectional shape of a flue of a diffuser inserted inthe airbag housing.

The invention will now be explained in further detail with reference tothe embodiments shown in the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view from below of a spread-out airbag for a passengerairbag module and an associated sword-like tool;

FIG. 2 shows the airbag according to FIG. 1 with a constriction and theassociated tools for compressing the airbag;

FIG. 3 shows a sectional view through FIG. 2 according to the lineIII-III;

FIG. 4 shows the folded airbag;

FIG. 5 shows a view from below of a spread-out airbag for a passengerairbag module with two associated sword-like tools;

FIG. 6 shows the airbag according to FIG. 5 with constrictions;

FIG. 7 is a plan view of the airbag for a driver airbag module with anassociated sword-like tool;

FIG. 8 shows the airbag according to FIG. 7 with constriction;

FIG. 9 is a view from below of a spread-out airbag for a driver airbagmodule with associated sword-like tools;

FIG. 10 shows the airbag according to FIG. 9 with constrictions and thetools for the compression of the airbag;

FIG. 11 shows the folded airbag according to FIG. 9;

FIG. 12 is a view from below of a spread-out airbag with constrictionsand associated wire-like tools for producing the constrictions;

FIG. 13 is a view from below of the spread-out circular airbag;

FIG. 14 is a plan view of a tool, partially cut away for constrictingthe airbag parallel to the plane of the spread-out airbag;

FIG. 15 is a sectional view through the tool according to FIG. 14 in thedirection of arrows XIV—XIV;

FIG. 16 shows the tool according to FIG. 15 with folded airbag;

FIG. 17 is a sectional view through a further embodiment of a tool;

FIG. 18 is a plan view of the tool according to FIG. 17;

FIGS. 19-21 show the tool according to FIG. 17 in successive stages ofthe airbag folding.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a spread-out airbag 1 which has a blow-in mouth 2 for atubular gas generator. In the event that the tubular gas generator ismounted in the airbag it should be fitted prior to the folding process.A sword-like tool 3 is associated with the spread-out airbag. Thespread-out airbag lies on a backing support 4 and is covered at the topby a vertically adjustable cover 5 (FIG. 3). The distance between thebacking support and the cover thereby corresponds to the desired heightof the folded airbag. In the embodiment the top side lb lies on thebacking support 4 and the lower side la with the blow-in mouth 2 lies onthe top.

Before the folding proceeds, the airbag is spread out over the backingsupport and stretched smooth. The cover 5 is then brought to therequired distance against the backing support. The first andsubstantially new step of the folding processes now consists in movingthe sword-like tool 3 between the backing support 4 and the cover 5towards the airbag 1. By means of this tool a constriction 6 is producedas shown in FIG. 2. The airbag then has the shape shown in FIG. 2 of atooth with two roots. The constriction represents a pre-orientation forthe following chaotic folding of the airbag. To this end the airbag iscompressed following the creation of the constriction by means of thesliders 7 to 11. In the present embodiment the airbag is firstcompressed by the sliders 7, 8 and 9 in one direction and thencompressed to the required size by the sliders 10 and 11 at right anglesthereto.

After the compression, the chaotically folded airbag has the shape shownin FIG. 4. It can be seen that the constriction 6 remains set during thecompression and at the end of compression so that separate folded areaswith chaotic folds 1 c are produced. The danger of parts of the airbagoverlapping one another during compression is thereby substantiallyreduced.

FIGS. 5 and 6 show the production of two constrictions 6a and 6 b bymeans of two sword-like tools 3 a and 3 b. After their action on theairbag, the airbag has the shape shown in FIG. 6 with constrictions ontwo sides.

FIG. 7 shows an airbag 16 a spread out for a driver airbag module whichis folded on one side in the shape shown in FIG. 8 by means of asword-like tool 3.

FIGS. 9 to 11 show how an airbag 16 b is pre-folded by means of foursword-like tools 12 to 15. As with the previous embodiments, the airbag16 b is spread out on a backing support (not shown) and covered by acover at the required distance from the backing support. Constrictions17 to 20 are then formed in the airbag by means of the sword-like tools.The airbag then has the shape shown in FIG. 10 of a four-leaf clover.The airbag is then compressed by means of the sliders 21 to 24 i.e., achaotic folding is achieved.

After compression, the airbag has the shape shown in FIG. 11. It can beseen that even in this case after folding, the constrictions 17 to 20are present. Through the division of the airbag into four partial areasby means of the constrictions, the risk of overlapping of the foldsduring compression is substantially reduced.

In the embodiment of FIG. 12 wire-like tools 25 to 28 are provided forproducing the constrictions in place of the sword-like tools. These wirelike tools are shown in section in FIG. 12 and extend through slits inthe backing support (not shown) and in the cover (not shown) and aredisplaced relative to the airbag by a drive which is known per se and isnot shown. The compression of the airbag to the size required forstorage in the airbag module is carried out as shown with the embodimentin FIGS. 9 to 11.

In FIG. 13, an airbag 29 is shown in the spread-out position which is tobe constricted parallel to the expansion plane and then gatheredtogether. As can be seen from FIG. 14, two slider-like tools 30, 31 areprovided by means of which the outer areas 32, 33 of the airbag 29 areconstricted to a gas generator 34 so that they have the position shownin FIG. 14. Gathering sliders 35 to 38 can be seen in this FIG.

As can be seen from FIG. 15, the airbag has in the area of theconstrictions upper parts 39 and lower parts 40 which are then foldedchaotically by means of the gathering sliders 35 to 38 which arerestricted top and bottom by cover plates 41, 42 wherein at least onecover plate should be movable for opening the folding space.

It can be seen from FIG. 16 that a separate folding of the upper parts39 and lower parts 40 is carried out by the gathering elements wherebythe advantages mentioned above are produced.

FIG. 17 shows a section through a tool which as in the embodiment ofFIG. 1 has a sword-like tool 3. This is guided between a lower coverplate 43 and an upper cover plate 44 and runs perpendicular to same. Inthe lower cover plate 43 is a cut out section for holding a housing 50in which the airbag having the diffuser 51 can be inserted. The diffuserhas a flue 52 which has outlet openings (not shown) for the gas emergingfrom the gas generator. The gas generator is fixed in the diffuserbefore or after folding the airbag. A packing ram 53 is positioned inthe cut out section in the upper cover plate 44 and a place holder 54 isguided in the packing ram whereby the cross-section of the place holdercorresponds in the direction of movement to the cross-section of theflue 52. As can be seen in FIG. 17, the place holder 54 lies on the flue52 whereby only the top side 1 b of the airbag 1 is fixed between thetwo, and the space above the flue is kept free during the entire foldingprocess so that the top side in the area of the flue 52 runs separatelyfrom the lower side 1 a. The separate path is ensured on the side of theflue 52 by a slider 55 which prevents the top and bottom sides fromoverlapping when folding the airbag.

The space between the cover plates is restricted at the side by sliders45 to 48. In FIGS. 17 and 18, the airbag 1 is shown already partiallyfolded whereby a constriction 6 is produced by the sword-like tool 3 andthe airbag has been brought by the sliders 47, 48 to the width requiredfor storage.

After the airbag has been prefolded in the manner shown in FIGS. 17 and18 it is further gathered by means of the sliders 45 and 46. In FIG. 19,the slider 45 is shown in its end position. The left of the airbag isfolded completely chaotically. The slider 46 has reached itsintermediate position and thereby the right airbag part is prefoldedchaotically. A fold 49 defined by the slider 55 thereby remains set.

For the further folding process, the slider 55 is drawn back from thespace between the cover plates 43 and 44 and the slider 46 is broughtinto its end position as shown in FIG. 20. Also in this folding state,the fold 49 remains and thus the separate position of the lower part 1 aand upper part 1 b remains between the place holder and the flue on oneside and the fold 49 on the other.

At the end of the gathering process, the gathered airbag is pressed bythe packing ram 53 past the flue 52 into the housing 50 as shown in FIG.21.

With this embodiment of the tool, apart from a separate folding by usingthe sword-like tool, it happens that in the area of the diffuser andmore particularly in the area of the outlet openings provided there, theupper and lower parts of the airbag do not overlap. The opening behaviorof the airbag is thereby subjected to an additional positive influence.

What is claimed is:
 1. A method for folding an airbag comprising:spreading out an unfolded airbag; constricting the spread-out airbag atleast once on at least one side perpendicular to the plane of thespread-out airbag; and folding the airbag to the size required forstorage in an airbag module wherein the constriction remains set, andwherein the airbag is folded separately in areas which are separated bya constriction.
 2. The method according to claim 1 wherein the airbag isconstricted from the upper to the bottom side.
 3. The method accordingto claim 1 wherein the airbag is constricted at right angles to theplane of the spread out airbag.
 4. The method according to claim 1wherein the airbag is constricted on several sides.
 5. The methodaccording to claim 4 wherein the constriction is carried outsimultaneously on all sides.
 6. The method according to claim 1 whereinthe airbag is constricted between its upper and lower sides.
 7. A devicefor folding a spread-out airbag, comprising: a constriction tool whereinthe tool is displaceable relative to the spread-out airbag in the planeof the spread-out airbag to produce a constriction in the airbag;folding tools adjacent the spread-out airbag to compress the airbag to astorage size; and a lower cover plate and an upper cover plate of whichone is movable, the upper and lower cover plates defining a space forfolding the airbag; wherein the constriction tool is an elongated toolthat is displaceable in the plane of the spread-out airbag in theelongated direction of the tool; wherein the elongated tool runs betweenthe cover plates and at right angles to same, wherein the space forfolding the airbag is restricted at the sides by the folding tools whichare movable between the cover plates, wherein the lower cover plate hasan opening for an airbag housing and next to this at least one slider isprovided which can be moved perpendicular relative to the cover plate,and wherein the upper cover plate has an opening in the area of theairbag housing in which is mounted a removable packing ram which ismovable perpendicular to the cover plates and contains a place holdermovable perpendicular to the cover plates.
 8. The device according toclaim 7 wherein the place holder has at right angles to the direction ofmovement roughly the cross-sectional shape of a flue of a diffuserinserted in the airbag housing.
 9. A device for folding a spread-outairbag, comprising: a constriction tool wherein the tool is displaceablerelative to the spread-out airbag in the plane of the spread-out airbagto produce a constriction in the airbag; and folding tools adjacent thespread-out airbag to compress the airbag to a storage size; wherein theconstriction tool is a wire; wherein the wire extends perpendicular tothe plane of the spread-out airbag.
 10. The device according to claim 9,wherein the wire is displaceable in the plane of the spread-out airbag.